I'm wondering whether an internship is required to be an entrepreneur, or whether at least it could be a key component of one's preparation. Say I want to start a business in fashion retail or in data storage. (Very different, I know.) Should I get an internship or a low-level job in that industry first to learn the ropes? Are there some industries in which it's more necessary than others? When is it advisable, and when is it not essential?

I know many factors go into the success of an entrepreneur like Steve Jobs (and maybe Jobs was truly unique), but I'm wondering what personality traits are central to that kind of success. What can I work on and cultivate in myself to be a better entrepreneur?